Today's Message Index:
----------------------
1. 07:45 AM - Re: Blowing fuses on B&C BC433 alternator (Sam Hoskins)
2. 09:22 AM - Re: Blowing fuses on B&C BC433 alternator (Robert L. Nuckolls, III)
3. 10:04 AM - Re: Blowing fuses on B&C BC433 alternator (Sam Hoskins)
4. 03:13 PM - Re: Blowing fuses on B&C BC433 alternator (Sam Hoskins)
5. 04:56 PM - Com radio malfunction (Janet Amtmann)
6. 06:05 PM - Re: Com radio malfunction (Jeff Luckey)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Blowing fuses on B&C BC433 alternator |
Here are both sides of the fuse in question. I see the leg of the fuse
that incurred the most melting is a bit corroded, for lack of a better
word. So perhaps, your theory may be correct about overheating.
I am wondering, does this device really need to be fused at all? That's
the discussion I'm having at B&C.
Thanks.
Sam
On Tue, Aug 17, 2021 at 10:26 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> About 50 flight hours ago, one of the fuses blew. Really blew, it
> partially melted
> the plastic coating. I couldn't really find anything wrong, but I thought
> possibly
> there was a short from one of the butt connectors to the firewall, nothing
> definitive though. Last week, 50 flight hours later, another fuse blew.
> I don't know if it was on the same leg as I didn't record it the first time
> it happened. All the wiring from the alternator to the VR seems to be 100%.
> I put my VOM on the leads and they all checked out per the B&C service
> manual. https://bandc.com/wp-content/uploads/2018/05/pmr3a-trouble.pdf
>
> It would be interesting to see the carcasses of
> the blown fuses. A design goal for fuses is to
> provide a benign mitigation to an overloaded
> wire. They are electrical 'weak links' in the
> energy conduction chain. Fuse (and breaker)
> manufacturers design and test their products
> striving to bring a potentially catastrophic
> failure to a ho-hum conclusion.
>
> If a blown fuse presents with a compromised
> enclosure then it seems likely that some condition
> other than fault current is in operation. Especially
> when two such events are widely spaced in time.
>
> Electrical connections inside holders for
> these fuses are close cousins to the fast-on
> style terminals. They depend on very high
> pressure mating to achieve gas-tight integrity
> at the interface between blade and terminal.
>
> As we've seen and studied on switch failures,
> loss of gas-tightness, over TIME, can produce
> electrically induced heating at the joint that
> contributes to a slow but ever increasing
> degradation that ends in rather spectacular
> failure of the whole assembly.
>
> This may well be what we're seeing here.
> The fuse didn't simply open up in response
> to some over-current, rather it may have
> failed in response to a precipitous heating
> event at the blade-to-terminal interface.
>
> Suggest you replace all three fuse holders
> and see how it goes.
>
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Blowing fuses on B&C BC433 alternator |
At 09:44 AM 8/19/2021, you wrote:
>Here are both sides of the fuse in question. I see the leg of the
>fuse that incurred
>the most melting is a bit corroded, for lack of a better word. So
>perhaps, your
>theory may be correct about overheating.
Yup!
>I am wondering, does this device really need to be fused at all?
>That's the discussion I'm having at B&C.
Good question. It would be interesting to
conduct an experiment on the bench to see
if shorting all three output leads together
produces fault currents that put the
alternator windings at risk.
We know that a wound-field alternator is
not capable of blowing it's own b-lead
protection . . . the magnetics are inherently
current limiting. I'm unable to articulate
a reason that PM alternators would be any
different.
It's an easy experiment to conduct on the
drive stand. You might query B&C as to their
rational for installing those fuses.
Did a quick search on 3-phase wiring for
motorcycles and outboards. Not one installation
depicted fuses in the alternator's AC
leads.
So I share your skepticism that is best
addressed with (1) testing and/or
(2) qualified advice/experience.
A part not installed is a part that cannot
become a maintenance issue.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Blowing fuses on B&C BC433 alternator |
Thanks Bob. If I hear back from B&C I'll let you know.
Sam
On Thu, Aug 19, 2021 at 11:27 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 09:44 AM 8/19/2021, you wrote:
>
> Here are both sides of the fuse in question. I see the leg of the fuse
> that incurred
> the most melting is a bit corroded, for lack of a better word. So perhaps,
> your
> theory may be correct about overheating.
>
>
> Yup!
>
> I am wondering, does this device really need to be fused at all?
> That's the discussion I'm having at B&C.
>
>
> Good question. It would be interesting to
> conduct an experiment on the bench to see
> if shorting all three output leads together
> produces fault currents that put the
> alternator windings at risk.
>
> We know that a wound-field alternator is
> not capable of blowing it's own b-lead
> protection . . . the magnetics are inherently
> current limiting. I'm unable to articulate
> a reason that PM alternators would be any
> different.
>
> It's an easy experiment to conduct on the
> drive stand. You might query B&C as to their
> rational for installing those fuses.
>
> Did a quick search on 3-phase wiring for
> motorcycles and outboards. Not one installation
> depicted fuses in the alternator's AC
> leads.
>
> So I share your skepticism that is best
> addressed with (1) testing and/or
> (2) qualified advice/experience.
>
> A part not installed is a part that cannot
> become a maintenance issue.
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Blowing fuses on B&C BC433 alternator |
UPDATE!!
TJ from B&C just called me and informed me that they have done away with
the three fuses and have revised the BC433 30 amp alternator drawing. The
new drawing is : https://bandc.com/wp-content/uploads/2021/08/505-501-.pdf
They did run an alternator on a test stand and found no good reason to keep
the fuses.
So, there you have it.
Thanks again.
Sam
On Thu, Aug 19, 2021 at 11:27 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 09:44 AM 8/19/2021, you wrote:
>
> Here are both sides of the fuse in question. I see the leg of the fuse
> that incurred
> the most melting is a bit corroded, for lack of a better word. So perhaps,
> your
> theory may be correct about overheating.
>
>
> Yup!
>
> I am wondering, does this device really need to be fused at all?
> That's the discussion I'm having at B&C.
>
>
> Good question. It would be interesting to
> conduct an experiment on the bench to see
> if shorting all three output leads together
> produces fault currents that put the
> alternator windings at risk.
>
> We know that a wound-field alternator is
> not capable of blowing it's own b-lead
> protection . . . the magnetics are inherently
> current limiting. I'm unable to articulate
> a reason that PM alternators would be any
> different.
>
> It's an easy experiment to conduct on the
> drive stand. You might query B&C as to their
> rational for installing those fuses.
>
> Did a quick search on 3-phase wiring for
> motorcycles and outboards. Not one installation
> depicted fuses in the alternator's AC
> leads.
>
> So I share your skepticism that is best
> addressed with (1) testing and/or
> (2) qualified advice/experience.
>
> A part not installed is a part that cannot
> become a maintenance issue.
>
> Bob . . .
>
> Un impeachable logic: George Carlin asked, "If black boxes
> survive crashes, why don't they make the whole airplane
> out of that stuff?"
>
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Com radio malfunction |
Can anyone help me with this?
I bought an Apollo/UPS GX65 GPS/COM back in the 90's new from the factory.
When I finished my RV6 I installed the radio and found that the COM side
was doa. The radio display showed it powering up. I checked all wiring
except for the antenna leads and found no wiring problems. I had someone
repair the radio (who replaced a component but won't tell me what the
actual problem was) and am now reluctant to install it again in case
it blows up again.
My question is: can an open or a short to ground in the antenna lead cause
the output circuits of the radio to fail? I plan to check the antenna lead
but it requires a major disassembly to get to the antenna connection.
I would appreciate any thoughts from the members. J=C3=BCrgen Amtmann
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Com radio malfunction |
Jurgen,
I'm not an RF expert so I defer to other Listers who are, but I can offer a
couple of "safe" suggestions:
1. you could hook-up the comm antenna and see if the radio receives any sig
nals.=C2- If you can hear comm traffic then that gives you an indication
that the antenna is working as some level.=C2- If you cannot receive anyt
hing, that may indicate bad antenna/wiring.
DO NOT transmit until you have an indication that the antenna & its wiring
are working at some level!
2.=C2- Having said that, it is my understanding that modern transmitters
can detect a bad antenna situation (like high SWR and probably a shorted an
tenna) and automatically shut-down the RF output before it destroys the out
put transistors.=C2- I don't know if your radio has this feature (my gues
s is it does, but you must verify)=C2- Regardless, you do not want to rel
y on this feature.
3. The ideal situation would be to bench test it with known good antenna &
feedline.
4.=C2- The next step would be to get an antenna analyzer or SWR meter.=C2
- There are apparently some very cool antenna analyzers available for < $
100.=C2- I think BobN mentioned some in some posts a few weeks (maybe mon
ths) ago.
-Jeff
On Thursday, August 19, 2021, 05:03:42 PM PDT, Janet Amtmann <jgamtmann
2@gmail.com> wrote:
Can anyone help me with this?I bought an Apollo/UPS GX65 GPS/COM back in t
he 90's new from the factory.=C2- When I finished my RV6 I installed the
radio and found that the COM side was doa.=C2- The=C2-radio display sho
wed=C2-it powering up.=C2- I checked all wiring except for the antenna
leads and found no wiring problems.=C2- I had someone repair the radio (w
ho replaced a component but won't tell=C2- me what the actual problem was
) and am now reluctant to install it again in=C2-case it=C2-blows up ag
ain.=C2-=C2-My question is: can an open or a short to ground in the ant
enna lead cause the output circuits of the radio to fail?=C2- I plan to c
heck the antenna lead but it requires a major disassembly to get to the ant
enna connection.
I would appreciate any thoughts from the members.=C2- J=C3=BCrgen Amtmann
=C2-
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|